1. Field of the Invention
The present invention pertains to mounting apparatus for hardness testers. Specifically, it pertains to apparatus for mounting dial gauges on load cell type hardness testers.
2. Brief Description of the Prior Art
Load cell type hardness testers conventionally comprise a housing in which is carried a load cell. The load cell is engageable at one end by an operating cam and a penetrator. The penetrator engages a plunger rod. The operating cam is normally provided with a handle, rotation of which allows a predetermined force to be applied to the penetrator to indent the material being tested. The load cell and the plunger rod respond in a predetermined fashion to the indentation of the penetrator in the material being tested. A dial gauge is attached to the tester for engagement with the opposite end of the plunger rod for measuring the response of the load cell to the hardness of the material being tested.
The mounting of the dial gauge on the tester is extremely critical. It must be mounted so that the dial indicator thereof is in a fixed relationship with the tester housing at all times. Such dial gauges are normally provided with a stem member at the base thereof and a reciprocating plunger member extending from the stem. In the past, the dial gauge has been attached to the tester with mounting apparatus which grips the stem member holding it in place. Such means of mounting may create problems by damaging the stem. In fact, the stem may be so damaged as to impair the reciprocation of the plunger member by which the mechanism operating the dial indicator is actuated.
Since the dial gauge must be occasionally removed for changing of load cells with different loads, recalibration, repair, or replacement, the mounting apparatus should be easily removed and reattachable so that the dial gauge is returned to the same relative position prior to removal. The attachment apparatus of the prior art is not easily removable and, when it is removed, it is almost impossible to reattach it in such a way that the dial gauge is in the same relative position with the tester as prior to removal therefrom.